24 hour polymerization shrinkage of resin composite core materials

Abstract

Purpose The study's purpose was to evaluate the 24‐hour polymerization shrinkage of resin composite core materials. Material and methods Eleven resin composite core material samples (n = 12) were evaluated using a non‐contact imaging device with measurements obtained over 24 h. Shrinkage values were determined corresponding to proposed times involved with CAD/CAM same‐day treatment and at 24 h. Shrinkage data was statistically compared using Friedman/Dunn's test for intragroup analysis and Kruskal Wallis/Dunn's test for intergroup analysis, all at a 95% level of confidence (α = 0.05). Results Mean results identified a wide volumetric shrinkage range with considerable similarity overlap. Inconsistent shrinkage behavior was evident and all materials reached maximum values before 24 h. No significant difference was observed during proposed digital same day all ceramic crown procedures, but some differences were noted at 24 h. Conclusions Under this study's conditions results were material specific, at times inconsistent, with wide variation. Shrinkage consistently increased for all products and it is not known if the continued shrinkage magnitude may compromise the stability and fit of all‐ceramic crowns at 24 h.

Decálogo de buenas prácticas para el uso y mantenimiento de las Unidades de Fotocurado LEDs

“…Este último, representa la fase en la que el biomaterial, por haber alcanzado cierta rigidez, se torna incapaz de escurrirse internamente y las moléculas ya no pueden desplazarse. (31,32) Existen diferentes modos de curado, (33,34) que buscan reducir el estrés inicial de contracción retrasando el punto gel. El objetivo es tratar de retardar la velocidad de curado de los polímeros, y permitir que se puedan liberar las tensiones internas.…”